Simultaneous atrazine degradation and E. coli inactivation by simulated solar photo-Fenton-like process using persulfate

ABSTRACT

This work evaluated the feasibility of a photo-Fenton-like process using persulfate (PS) and ferrous iron (Fe²⁺) under simulated solar radiation for degrading the herbicide atrazine (ATZ, 6-Chloro-N-ethyl-N′-isopropyl-1,3,5-triazine-2,4-diamine) and inactivating E. coli. Milli Q water, lake water, and diluted wastewater effluents were spiked both simultaneously and separately with ATZ (4 mg/L) and E. coli (10⁵ CFU/mL), and exposed to treatment. A method for determining the average irradiance throughout the water media in the UV(A+B) range of the Xe lamp emission was developed for bench-scale experiments. These values were used to calculate the UV(A+B) fluences and the solar UV(A+B) energy doses per unit of volume (Q_UV(A+B), kJ/L). The obtained kinetic data were presented versus energy dose. Treatment of lake water at near-neutral pH was ineffective via the photo-Fenton-like process, attaining only 20% ATZ removal and 1-log reduction of E. coli. In Milli Q water and wastewater, the complete degradation of ATZ in the absence of bacteria was observed at an average energy dose of 1.5 kJ/L (60 min), while in the presence of cells the degradation efficiency was ∼60%. When ATZ was present, E. coli inactivation was also affected in Milli Q water, with 1.4-log reduction (93%) at a dose of 1.6 kJ/L (60 min), whereas in wastewater complete inactivation was achieved at a lower dose of 1.3 kJ/L (45 min). The energy requirements on a Q_UV(A+B) basis for simultaneous 90% ATZ removal and 99.99% E. coli inactivation in Milli Q water and wastewater were shown to be less than 10 kJ/L. This suggests the solar/PS/Fe²⁺ system is promising for simultaneous treatment and disinfection of wastewater effluents.

KEYWORDS:

• Atrazine
• E. coli
• persulfate
• simultaneous treatment
• solar photo-Fenton
• water

Funding

The authors acknowledge financial support from the Russian Science Foundation (Grant No. 14-14-00279). Dr. Sara Beck's visit was supported by the Russian Foundation for Basic Research (Grant No. 14-38-50562).